Core-loss behavior of Fe-based nanocrystalline at high frequency and high temperature

We measured the loss of Fe_73.5Si_15.5B₇Cu₁Nb₃ nanocrystalline magnetic cores prepared by winding an amorphous alloy ribbon into a ring and annealing at 550 °C for 1 h. The dynamic loss of the magnetic core was tested in an oil bath environment from 30 to 200 °C, with a frequency range from 10 to 100kHz and at B_m = 300mT. The coercivity, magnetic induction and permeability of the core deteriorate as the ambient temperature rises. At 100 kHz, the loss decreases from 75.87 W/kg to 72.34 W/kg when temperature increases from 30 to 130 °C and then increases to 73.65 W/kg when temperature increases to 200 °. The loss of the magnetic core shows a trend of first decreasing and then increasing with ambient temperature, and the trend becomes stronger at higher frequencies. Based on Bertotti’s loss separation theory, the reduction of excess loss is the main reason for the reduction of core loss at high temperature, and the excess loss and hysteresis loss are in a competitive relationship. The reason for the decrease in excess loss is thought to be the rise in coercivity.